1. Field of the Invention
This invention pertains to an implant for passing blood flow directly between a chamber of the heart and a coronary vessel. More particularly, this invention pertains to such an implant with an enhance design for providing blood flow to septal perfusing and branching arteries.
2. Description of the Prior Art
Commonly assigned and co-pending U.S. patent application Ser. No. 08/882,397 filed Jun. 25, 1997, now U.S. Pat. No. 5,944,019, entitled "Method and Apparatus for Performing Coronary Bypass Surgery", and filed in the name of inventors Mark B. Knudson and William L. Giese, teaches an implant for defining a blood flow conduit directly from a chamber of the heart to a lumen of a coronary vessel. An embodiment disclosed in the aforementioned application teaches an L-shaped implant in the form of a rigid conduit having one leg sized to be received within a lumen of a coronary artery and a second leg sized to pass through the myocardium and extend into the left ventricle of the heart. As disclosed in the above-referenced application, the conduit is rigid and remains open for blood flow to pass through the conduit during both systole and diastole. The conduit penetrates into the left ventricle in order to prevent tissue growth and occlusions over an opening of the conduit.
Commonly assigned and co-pending U.S. patent application Ser. No. 08/944,313 filed Oct. 6, 1997, now U.S. Pat. No. 5,984,956, entitled "Transmyocardial Implant", and filed in the name of inventors Katherine S. Tweden, Guy P. Vanney and Thomas L. Odland, teaches an implant such as that shown in the aforementioned '397 application with an enhanced fixation structure. The enhanced fixation structure includes a fabric surrounding at least a portion of the conduit to facilitate tissue growth on the exterior of the implant.
Implants such as those shown in the aforementioned applications include a portion to be placed within a coronary vessel and a portion to be placed within the myocardium. When placing a portion of the implant in the coronary vessel, the vessel is axially incised a length sufficient to insert the implant. When placed within the coronary vessel, the implant discharges flow axially into the vessel. The vessel may have multiple branching vessels. For example, in the case of a coronary artery, numerous septal perfusing arteries may branch off of the coronary artery to provide blood to the septal wall. The septal perfusing arteries branch off of the floor of the coronary artery. In addition to these, additional small arteries may branch off of the sides of the coronary artery. Due to the axial length of the implant within the vessel, the wall of the implant may block blood flow to these branching arteries resulting in localized ischemia.